1. Field of the Invention
The present invention relates to a TFT array substrate and a liquid crystal display panel having the same.
2. Description of the Related Art
Liquid crystal displays (“LCDs”) display images by adjusting the light transmittances of liquid crystal cells arranged on an LCD panel in a matrix form according to video signals. Wide-viewing angle technology is applied to LCDs in order to overcome image distortion.
To obtain a wide viewing angle, the LCDs may employ a multi-domain vertical alignment (“MVA”) mode, a patterned ITO VA (“PVA”) mode, a superpatterned ITO VA (“S-PVA”) mode, and a micro-slit VA mode depending on a domain formation process. In the VA mode, liquid crystal molecules, which have a negative dielectric anisotropy, are arranged and driven perpendicular to the direction of an electric field to adjust the light transmittance.
The PVA mode, which is a VA mode using a slit pattern, forms a multi-domain structure by forming slits, which create fringe electric fields, on a common electrode and pixel electrodes of an upper substrate and a lower substrate, respectively, which then causes the liquid crystal molecules to be driven symmetrically with respect to the slits using the fringe electric fields.
The PVA mode, which further includes a common electrode patterning process in contrast to the other modes, exhibits a weakness against static electricity and also displays a poor distribution of optical characteristics due to the misalignment between the upper substrate and lower substrate. The above problems become increasingly serious as the size of the LCD increases.
The patternless VA mode does not provide slits on the common electrode of the upper substrate. The patternless VA mode does not include the step of patterning the common electrode on the upper substrate, and therefore, slits are provided only on the pixel electrodes of the lower substrate to drive the liquid crystal molecules.
Recently, the S-PVA mode has been intensively studied as an approach to further improve the visibility of LCDs. The S-PVA mode, which is classified into a TT-SPVA mode and a CC-SPVA mode, improves visibility by dividing a pixel into a main portion and a sub-portion and making one portion different from the other in brightness. However, the TT-SPVA mode is disadvantageous for having a reduced aperture ratio because more than two TFTs are required. Moreover, the overall response time in the TT-SPVA mode is slow since lower voltages are applied to the sub portion.